One-Shot: The Rat King (Beginners Welcome)

A restless teen with an adventurer’s spirit has gone missing. His father, a blacksmith named Ilfen Halfheart, fears that the boy got lost in a nearby cave network after hearing rumors that some sort of treasure might be down there. He is willing to pay what little reward he can for the boy's rescue, but there is a complication.

An ambitious were-rat alchemist known only as “the Rat King” set up a base of operations down in these caverns a year ago. He has been working tirelessly in his laboratory since then, using alchemy and magic to mutate and breed loyal rat minions to suit his needs.

Howdy! I'm running a low level one-shot. New or returning players to 5e, Roll20, D&D, or Tabletop in general are welcome, as I feel this is a nice adventure to start with.
Characters will be 1st level.
All sourcebooks and UA are fine by me, but no homebrew
Pre-made characters are available if necessary
Game will be July 27th, 3 pm CST (Costa Rica time)
Discord will be used for voice chat